Field of the Invention
This invention relates to the field of manufacturing integrated circuits. More particularly, this invention relates to the use of direct write lithography techniques as part of integrated circuit manufacture.
Description of the Prior Art
It is known to manufacture integrated circuits using a sequence of masks for forming different layers within the integrated circuit. The manufacture of suitable masks is a time consuming and expensive operation.
It is known to utilize direct write lithography during the manufacture of integrated circuits. In particular, it is known to use techniques such as direct write electron beam lithography to correct manufacturing defects in individual integrated circuits that have been manufactured. As an example, if an integrated circuit has been manufactured with a short circuit between two printed features, then direct write electron beam lithography may be used to remove that short circuit and restore proper operation to the integrated circuit. Such operations provide defect correction within a fixed layout design.
Other direct write lithographic techniques are known. These include inkjet circuit printing and aerosol jet circuit printing. These techniques are becoming increasingly capable of producing circuits of small size to the extent that they may be used to manufacture integrated circuits.
A problem that is increasing as process size decreases in integrated circuit manufacture is that of unwanted variability in the size and positioning of circuit features. This can reduce the yield of correctly operating integrated circuits and adversely affect the performance characteristics of integrated circuits taking them outside of a desired range.